The connection between metabolic health and cognitive function is undeniable—and the increasing recognition of Alzheimer’s as “type 3 diabetes” by organizations like the National Institute of Aging showcases how important it is to take care of our metabolism to protect our brain.
Recent research has revealed a significant overlap between insulin resistance, metabolic dysfunction, and the development of brain degeneration. Just as insulin resistance is at the core of type 2 diabetes, that dysfunction appears to trigger processes in the brain that disrupt cellular health and neuron function and contribute to Alzheimer’s.
So, how exactly does this connection work—and what can we do to support both our cognitive and metabolic health? Below, we’ll take a deeper look into the science, plus lifestyle factors that can help us maintain a healthy brain and metabolism.
- ABOUT OUR EXPERTS: Dr. Chelsea Azarcon, N.M.D., is a naturopathic physician. Dr. Jolene Brighten, N.M.D., is a board-certified naturopathic endocrinologist.
The Link Between Metabolic Health and Cognitive Function
Poor metabolic health is a growing epidemic, with conditions like obesity, insulin resistance, and type 2 diabetes on the rise. These metabolic issues affect not only our physical health, but are also now recognized as key contributors to cognitive decline (or cognitive impairment), which describes an often gradual loss of thinking abilities, such as memory, learning, attention, and reasoning.
In fact, insulin resistance has been linked not only to type 2 diabetes but also to the development of Alzheimer’s.
“Insulin is a hormone that helps your body use glucose (sugar) for energy. When the body becomes resistant to insulin, it can’t use glucose effectively, which increases blood sugar levels,” says Brighten. This can then impact the brain in multiple ways.
For one, experts suggest type 2 diabetes-related blood vessel damage (a downstream effect of unmanaged blood sugar) may contribute to cognitive decline by impairing blood flow to the brain.
It can also promote the development of plaques and protein tangles that disrupt cognitive function, suggests naturopathic physician Dr. Chelsea Azarcon, N.M.D. “Alzheimer’s is now sometimes called type 3 diabetes because protein tangles that interrupt nerve firing and ultimately lead to brain cell death are believed to be triggered, at least in some cases, by insulin resistance,” she explains.
Major Causes of Insulin Resistance
According to the American Diabetes Association, insulin resistance—now considered a major risk factor for Alzheimer’s—is often caused by a combination of diet and lifestyle factors, including excess sugar intake, obesity, smoking, excessive alcohol intake, and family history of metabolic disorders.
While adults over 45 are most likely to develop insulin resistance, it can affect younger folks, particularly those with poor metabolic health.
Insulin Resistance, Inflammation, And Cognitive Decline
Excessive insulin can also lead to problems like oxidative stress, inflammation, mitochondrial dysfunction, and reduced cellular repair mechanisms like autophagy, all of which are driving forces of cognitive issues, according to Dr. Jolene Brighten, N.M.D., a board-certified naturopathic endocrinologist.
The relationship between insulin resistance and inflammation seems to be particularly problematic for long-term brain health. “Insulin resistance is often triggered by inflammation,” explains Azarcon. Meanwhile, inflammation in the brain can also exacerbate the damage caused by existing insulin dysregulation. Talk about a vicious cycle.
The issue with chronic inflammation? It can make it difficult for the body to repair itself—and when it affects the brain, it can contribute to cognitive issues like memory loss, mood changes, and, eventually, the inability to perform everyday tasks.
In the presence of chronic inflammation, microglia (the brain’s immune cells) can also become overactive, damaging healthy neurons and forming harmful protein tangles that contribute to the progression of Alzheimer’s, the experts explain.
How to Support Both Metabolic and Brain Health
The good news is that there are several steps you can take to protect your brain health by way of your metabolic health. Here’s a look at a few must-do’s for promoting healthy insulin function and cognitive longevity.
1. Eat Anti-Inflammatory, Low-Glycemic Foods
A diet rich in anti-inflammatory foods can help combat the damage caused by insulin resistance and support brain function, according to Azarcon, who recommends eating unprocessed foods like leafy greens and other veggies, berries, nuts, seeds, and omega-3-rich foods like wild-caught salmon.
Meanwhile, low-glycemic foods rich in nutrients and fiber—such as whole grains, berries, beans, and sweet potatoes—help keep blood sugar levels stable without spiking insulin levels, according to Azarcon. A diet based on these foods wards off inflammation and insulin dysfunction to protect metabolic and cognitive health.
Read More: 7 Ways To Make Your Carb Consumption More Blood Sugar-Friendly
In one study, adults who followed a Mediterranean diet (high in anti-inflammatory and low-glycemic foods) had thicker cortical brain regions than those who did not. These brain regions were found to have shrunk in people with Alzheimer’s, suggesting a relationship between their thickness and cognition. A follow-up study also found that people not following a Mediterranean diet exhibited impaired glucose metabolism and higher levels of beta-amyloid protein (both seen in Alzheimer’s patients).
2. Balance Meals With Plenty of Protein
“One recommendation I make in my clinic is to eat protein with every meal,” says Brighten. Why? High-protein foods, like beef, fish, and certain dairy products (like yogurt), help to balance blood sugar and are more filling than sugary snacks.
Ideally, Brighten recommends aiming for about 30 grams of protein with each meal and ideally about 100 grams per day.
Otherwise, ensure blood sugar stability and healthy insulin function by avoiding refined carbohydrates and filling half your plate with fiber-rich vegetables over starchy options like potatoes.
3. Hail Healthy Fats
Docosahexaenoic acid (DHA) is an omega-3 fatty acid that accumulates in the brain and helps maintain healthy brain tissue. Ample DHA has been linked to improved cognitive abilities, while deficiencies have been associated with ADHD, depression, and an increased risk of cognitive decline.
Getting your fill of this omega-3 is a good move if cognitive health is top of mind. One excellent source? Salmon. Azarcon recommends wild-caught “because it often contains fewer toxins, like mercury, than farmed fish.” Adding this food to your diet can be a simple but effective way to nourish your brain with the fats it needs for healthy cognition. If seafood doesn’t regularly make its way onto your plate, consider a high-quality fish oil supplement.
Flaxseeds and walnuts also provide healthy fats in the form of another omega-3, alpha-linolenic acid (ALA), which also helps support brain health. Flaxseeds, specifically, promote neuroplasticity, the brain’s ability to grow new nerves and adapt. (Fun fact: You can load up on flax via liquid and capsule supplements if you’re not much of a seed eater.) Meanwhile, studies have shown that walnuts can prevent the formation of protein plaques in the brain (which are characteristic of Alzheimer’s disease).
Finally, Azarcon suggests consuming avocado and olive oil regularly, as they are great sources of fat called oleic acid, a major component of brain and nerve cells. “Higher dietary intake of oleic acid may help protect against cognitive decline,” she notes.
4. Consider Intermittent Fasting
Intermittent fasting has gained popularity as a strategy to improve metabolic function and potentially help manage diabetes. “Fasting is a great way to help reset insulin resistance,” says Azarcon.
Recent studies suggest fasting and caloric restriction may have significant benefits for brain health, too, particularly related to Alzheimer’s disease, due to their ability to reduce β-amyloid accumulation, a key marker of Alzheimer’s. The research also suggests they improve cognitive function by enhancing synaptic adaptations in the hippocampus.
Read More: 5 Signs Intermittent Fasting Is Working For You—And 5 Signs It’s Not
Intermittent fasting gives the body periods of rest from food, decreasing insulin levels and helping the body become more sensitive to insulin, Brighten explains. She suggests starting with shorter fasting periods of about 12 hours (including overnight) and gradually increasing if desired. Be sure to eat balanced meals with plenty of fiber and protein before and after fasts to give your body enough energy and support stable blood sugar levels.
5. Exercise Regularly
An article published in the Journal of Sport and Health Science states: “Older adults who exercise are more likely to maintain cognition.” A few potential reasons: Exercise impacts amyloid β turnover, works against inflammation, and improves cerebral blood flow.
Physical activity can also help manage blood glucose and insulin sensitivity, according to Azarcon. “Even exercise as simple as a walk after a meal can increase glucose uptake by the muscles, which gets it out of the blood,” she explains.
That said, overall, “both cardiovascular exercise and strength training are important for maintaining a healthy metabolism due to how they help build muscle, fight inflammation, support hormonal balance (including insulin sensitivity), and promote fat loss,” notes Brighten.
She advises a weekly combination of aerobic exercises like brisk walking, running, cycling, and swimming with resistance training for building and preserving metabolism-boosting muscle.
6. Cut Down On Alcohol
According to the Alzheimer’s Society, people who drink heavily are at higher risk for developing dementia and Alzheimer’s due to its adverse effects on important brain regions.
Excessive alcohol consumption may also increase the conversion of estrogen to androgen hormones, exacerbating hormonal imbalances and potentially increasing the risk of cognitive decline, adds Brighten.
Reducing alcohol intake offers numerous benefits by helping with weight management and lowering inflammation—good things for metabolic function and brain health. Both Azarcon and Brighten recommend sticking to one drink per day or less.
7. Keep Stress Under Control
Chronic stress can negatively affect both metabolism and cognitive function. Prolonged stress leads to elevated cortisol levels and inflammation, which can impair brain function and contribute to insulin resistance, says Brighten.
She and Azarcon both recommend finding ways to manage stress, such as practicing mindfulness, meditation, or yoga. “Managing stress is essential for balancing blood sugar levels and protecting the brain from the negative effects of chronic cortisol exposure,” says Brighten. Additionally, keeping stress in check can help you make better food choices and sleep more soundly, which supports metabolic health.
If you need a little extra support in this department, consider herbs like cortisol-busting ashwagandha and nervous system-soothing lemon balm.